Fabrication of ultrathin artificial basement membrane for epithelial cell culture

Basement membranes are essential for epithelial and endothelial tissue organization. To mimic them, we developed a fabrication method to produce ultrathin membrane of collagen IV and laminin. A honeycomb microframe of thickness 50 mu m and compartment-size 400 mu m was firstly patterned in polyethylene glycol diacrylate (PEGDA) by using lithography and vacuum assisted UV curing techniques. Then, a monolayer of gelatin nanofibers was electrospun and crosslinked on the microframe to form a secondary structure, a fiber mesh with much smaller pore sizes, in each of the honeycomb compartments. Finally, a collagen IV-laminin gel layer was deposited and dehydrated, leading to the formation of ultrathin membrane over a large area with a nanofiber backbone. Such an artificial basement membrane is mechanically stable and fully bio-compatible. It is also semipermeable which can slow down considerably the diffusion of large size molecules. More importantly, it can be used to improve the monolayer formation of epithelial cells. Thus, this culture device recapitulates the biological basement membrane, permits the epithelial tissue formation, and allows mimicking a sophisticated cellular microenvironment.